Primary and secondary battery.



UNITED STATES PATENT ossios.

THOMAS A. EDISON, OF LLEWELLYN PARK, ORANGE, NEW JERSEY, ASSIGNOR EDISONMANUFACTURING COMPANY, OE WEST ORANGE, NEW JERSEY, A CORPORATION OF NEWJERSEY.

PRIMARY, AND SECONDARY BATTERY.

Specification of Letters Patent.

Patented July 2, 1907.

Application med January 10.1906. Serial to. 295,472.

To all whom it mag concern:

Be it known that I, THOMAS ALVA EDISO a citizen of the United States,residing at Llewellyn Park, Orange, in the county of Essex and State ofNew Jersey, have invented certain new and useful Improvements in Primaryand Secondary Batteries, of which the following is a description.

My invention relates to primary and secondary batteries of the typeemploying an alkaline electrolyte and wherein one of the activematerials, during the discharge is dissolved in the electrolyte, asuitable depolarizing material being used furnishing oxygen ondischarge. An example of a primary battery of this type is the wellknown Lalande element wherein the plated out of the alkaline zincatesolution by'the chargingcurrent. With such a secondary battery,ondischarge the nickel hydroxid will be reduced to a lower condition ofoxidation, and the metallic zinc will be oxidized and dissolved in theelectrolyte from which it will be again plated out on the next chargingoperation. 4

My present invention is based on the discovery that if an alkalinesilicate, preferably silicate of potash,

is added to the electrolyte of batteries of the type referred to, 'thesolvent power or capacity of the solution A as forzinc is very largelyincreased and may be made actually more than twice that of the usualalkaline hydrate alone. This permits the battery cells to be madeconsiderably smaller than heretofore in orde to obtain a given amperecapacity.

In the case of the Lalande combination, using copper oxid opposed tometallic zinc, the best composition for the electrolyte is to add to atwenty per 'cent solution of potassic hydrate, about fifteen per cent ofsilicate of potash. In other words, each one hundred cubic centimetersof the solution contains twenty grams of solid hydrate of potash, towhich is added fifteen grams of powdered silicate of potash; but it willbe of course understood that the proportion of in of the alkalinesilicate can be conveniently increased, since there is less likelihoodof the solution freezing than with .a primary battery, which latter areordinarily used in moreexposed places, such as for railroad signaling.The employment of the new electrolyte in connection with an alkalinezincate reversible battery, reduces the weight of such batteriesconsiderably. p p I It will of course be understood that the improvedelectrolyte may be used in any alkaline zincate bat- '-tery, eitherprimary or secondary, and that any suitable active depolarizing materialmay be employed, such as oxide of copper, silver or mercury or thehydroxids of nickel or cobalt. 1

I am not able to explain with absolute certainty the causeof the verysuperior results which are secured when an alkaline silicate is added tothe solution as above explained, but I believe the results are dueto thefact that the oxid of zinc formed on discharge is converted into adouble salt of siliconand potassium (silico-zincate of potash) which ismuch more soluble in the alkaline solution than the single salt ofzincand potassium, orthat silicate of zinc is formed which is solubleand forms a double salt with the alkali, and consequently less ofthelectrolyte may be used to hold the dissolved metal in solution.

I have referred particularly to the use of silicate of. potash as thepreferable alkaline silicate for-the-purpose, since I have secured'thebestv results with this material when added to a solution of potassiumhydrate asexplained. Very good results may be secured, however, withsilicate of soda in a potash solution, although not quite so good aswith silijcate of potash. In solutions of soda, the addition of analkaline silicate results in very little improvement.

Having now'described my invention, what I claim as new and desire tosecure by Letters Patent is as follows:

1. An alkaline battery electrolyte containing an alkaline silicate, asset forth.

'2. An alkaline battery electrolyte cont'ainlngsillcate of potash,substantially as set forth.

3. A battery electrolyte containing potassium hydrate and an alkalinesilicate, as set forth.

4. A battery electrolyte containing potassium hydrate 1()( and potassiumsilicate, as set forth.

5. In a battery, the combination of an electrode employing metalliczinc, a second electrode employing a de polarizing mass, and an alkalineelectrolyte containing an alkaline-silicate, substantially as setforth.

6. In a battery, the combination of an electrode employing metalliczinc, a second electrodeemploylng a depolarizing mass, and an alkalineelectrolyte containing silicate of potash, substantially as set forth.

7. In a reversible battery, the'comblnatlon ofan elec- 110 trodeemploying metallic zinc, a second electrode employlng nickel hydroxid asa depola rizer, and an' alkaline electrolyte containing an alkalinesilicate, substantially 5 set forth.

9. In a reversible battery, the combination of an electrode plate ofmetallic magnesium, a second electrode employing a depolarizing mass,and an alkaline zincate electrolyte containing an alkaline silicatesubstantially 10 as set forth.

10. In a reversible battery, the combination of an electrode plate ofmetallic magnesium, a second electrode cmploying a depolarizing mass,and an alkaline zincate electrolyte containing silicate of potash,substantially as set forth.

This specification signed and witnesscd this Utli (lay of Jany. 190G.

TIIOS. A. EDISON. Witnesses.

FRANK 13. Dyna, ANNA R. KLllllM.

